This invention generally relates to tools for driving tamper resistant screws and, more particularly, to tools having a bit end readily engageable with slots provided in the peripheral surface of the heads of the tamper resistant screws.
Many types of tamper resistant screws and complementary tools for installing and removing such screws have been disclosed in the past. Screws in this category normally include some type of slotted or recessed heads. The heads of the screws usually have some variation of a cruciform or similar shape adapted to be engaged by a complementary shaped bit end of a driving tool. In such arrangements, when torque is applied to the heads of such screws, the radial outer portion of the slots or recesses and the tips of the driving tool are caused to accept a major portion of the torque force, thus producing high unit loading. A continuing problem, in such arrangements, has been the lack of ability to apply torque to such screws without destroying the heads of the screws or the driving bit of the tools.
Heretofore, the ability of driving tools to withstand torque forces has been limited and often times, fatigue failure of driving tools is encountered upon repeat use. Another problem is that in many applications the driving tool is easily cammed out of the slots or recesses during a torquing operation, even when very high axial loads are applied to the driving tool in an attempt to hold the driving tip of the tool in place.